Biomineralization is when plants and animals make natural minerals like teeth or shells. We know what minerals like calcium and iron look like when they are found in rocks and the ground, but when plants and animals make their own minerals they are usually bigger and stronger than normal minerals. The minerals they make are usually the same shape and size, which helps plants and animals to be strong and keep themselves safe from danger. Animals like clams and oysters make shells made from minerals like calcium, which helps protect them from predators. Plants may make strong roots, stems and leaves from minerals to help them stay healthy and live longer. So biomineralization is like when plants and animals build their own minerals for protection!